The invention concerns a stable, standing, essentially rectangular form of a pack made from thin film or membrane-like material which uses a minimum of film area in relation to the volume of the contents of the pack and which because of its structural form can also use thinner film or membrane material than existing standing pouches, and to which various known and new types of top designs can be applied to facilitate opening and resealing or reclosing.
Further, the invention is concerned with a pack design that can be filled and sealed at high speeds comparable to the filling and sealing speeds of metal cans and glass jars, this ability being achieved by the special form of the base of the invention taken together with the method of manufacture of the pack which achieves an open box-like form that is stable and capable of being handled and transported at high speeds by means of conveyors.
Many forms of thin film or membrane packs are known, amongst them several forms of standing pouches. Concerning standing pouches, all of them have complex forms in the area of the bottom or base of the pack, such forms being necessary to give the pack some form of standing stability, particularly when filled with liquids. Because of these complex base configurations, all of these packs use more film or membrane than the invention, for a given filled volume. Moreover, some of these existing pack forms have vertical stiffening ribs to lend stability to the pack, but this stability is weakened in some cases by the method of folding the sides under to form the base of the pack, and in other cases by the means with which the walls are joined to the base, with the result that a stiffer film or membrane must be used to achieve the desired stability.
In regard to filling and sealing, all of these existing forms of standing packs use handling, filling and sealing systems which were developed specifically for known film type structures and which utilise single or up to about four filling heads which in turn limit the rate at which they can be filled and sealed to about 120 units per minute. This rate has been acceptable for the markets found for such packs but which is not acceptable for the high volume packaging required for many mass produced food and other products where rates of up to 2000 units per minute are required. Such high rates can only be achieved by multiple head rotary and in-line filling systems such as are used for the filling of bottles, jars and cans, which pack forms are in themselves stiff, stable standing packages exhibiting the necessary form stability for high speed handling. To date, no means has been found to utilise the existing forms of thin film flexible packs in such filling systems.
With recent progress in the development of special films capable of withstanding the high temperatures used in the cooking or autoclaving of food products packed in jars and cans, it is now possible to consider the use of thin film packs for such products, but it is not possible to achieve the required filling rates as explained above.